Quercetin inhibits truncated isoform of dopamine-and cAMP-regulated phosphoprotein as adjuvant treatment for trastuzumab therapy resistance in HER2-positive breast cancer

Trastuzumab resistance is one of the causes of poor prognosis in patients with human epidermal growth factor receptor 2(HER2)-positive(HER2+)breast cancer(BC).The truncated isoform of dopamine-and cAMPregulated phosphoprotein(t-DARPP)has been reported to be involved in trastuzumab therapy resistance and promoting tumor progression.To evaluate the t-DARPP expression in BC,paired tumors and surrounding normal tissues were analyzed by real-time polymerase chain reaction and confirmed higher DARPP-32 kDa family mRNA expression in HER2+BC tumor tissues.We established 2 patient-derived xenografts(PDX)mice models to test the efficacy of trastuzumab,named model 1(non-responder)and model 2(responder).t-DARPP and p95-HER2 protein-protein interactions were detected in PDX tumor tissue from non-responders using Förster resonance energy transfer assays.Instead,there is no response from the responder.Furthermore,mechanistic studies using transwell and western blot assays demonstrated that t-DARPP could upregulate epithelial-mesenchymal transition signaling proteins,enhance p95-HER2 expression and promote cell migration.We found that quercetin effectively reduced t-DARPP expression in HER2+BC cells.In t-DARPP ShRNA-suppressed cells,quercetin synergistically enhanced trastuzumab-induced apoptotic cell death and G2/M phase arrest.In conclusion,the combination of quercetin and trastuzumab treatment by targeting t-DARPP in HER2+BC patients has the potential as a biomarker for mitigating drug resistance.

A novel short transcript isoform of chicken IRF7 negatively regulates interferon-βproduction

Type I interferon(IFN-I)provides an important first line to protect avian species against pathogens invasion.IFN regulatory factor 7(IRF7)has been identified as the most important regulator for both DNA and RNA virus-induced IFN-I production in chickens.Although four splicing variants of IRF7 have been identified in mammals,it is still unclear whether alternative splicing patterns and the function of IRF7 isoform(s)exist in chickens.In this study,we reported a novel short transcript isoform of chicken IRF7(chIRF7),termed chIRF7-iso,which contained an intact N-terminal DNA-binding domain(DBD)and 14 amino acids different from chIRF7 in the C-terminal.Overexpression of chIRF7 in chicken leghorn male hepatocellular(LMH)cells activated the IFN-βpromoter and significantly inhibited Newcastle disease virus(NDV)and fowl adenovirus serotype 4(FAdV-4)replication.Conversely,overexpression of chIRF7-iso blocked the IFN-βpromoter activity and was favorable for NDV and FAdV-4 replication in vitro.Collectively,our results confirm that a novel chIRF7 isoform-mediated negative regulates IFN-βproduction,which will contribute to understanding the role of chIRF7 in innate antiviral response in chicken.

Phosphorus Starvation-induced Expression of Leaf Acid Phosphatase Isoforms in Soybean

Leaf acid phosphatase (APase) activities of 274 soybean genotypes were surveyed under field conditions with two levels of P supplies, and a nutrient solution culture experiment with eight selected genotypes was subsequently conducted under greenhouse conditions to further characterize APase activity and its isoform expression induced by P starvation. Results from the field experiment showed that there was a great genotypic variation for leaf APase activity among the tested soybean genotypes from different origins, and APase activity in many of the tested genotypes (about 60%) was generally increased in the treatment without P fertilizer addition. Results from the nutrient solution culture experiment showed that APase activity in all the eight tested genotypes was generally enhanced by P starvation. Six isoforms of APases were detected in isoelectric focusing gels with samples from both young and old leaves. The activity of all the six isoforms was increased by P starvation, but no new APase isoform was induced. Our results suggest that leaf APase activity could serve as an enzymatic indicator of P starvation for soybean; the increase in leaf APase activity under low P stress was mainly caused by the increase in the activity of existing isoforms but not by the induction of new isoforms.

Differential Expression of PKC Isoforms and Their Tumoricidal Activity in Two Macrophage Cell Lines: Involvement of Nitric Oxide-dependent Mechanisms

Objective: To investigate the role of PKC isoforms in the regulation of LPS-triggered tumoricidal activity in macrophages and further elucidate its signal mechanisms. Methods: Two macrophage cell lines (P388D1 and RAW264.7) were stimulated by LPS alone, or with long-term of PMA pretreatment. Then cytotoxicities to P815 cells (by MTT assay) and IL-1, TNF- (by ELISA) and nitric oxide (NO) production (by Griess reagent) in supernatants were measured. Western blot for PKC isoforms after long-term PMA pretreatment was analyzed. Results: RAW264.7 cells were stimulated with LPS to kill target tumor cells P815, whereas P388D1 cells failed to develop such an ability. Down-regulation of PKC isoforms by chronic treatment with PMA significantly inhibited the LPS-induced cytotoxicity in RAW264.7 cells. In unstimulated state, Western blotting with rabbit antiserum specific for the PKC, 1, 2, or showed all 5 isoforms were detected in P388D1 cells, while only PKC, PKC1 and PKC were detected in RAW264.7 cells. Exposure of the cells to long-term of PMA treatment significantly down-regulated the expression of PKC, PKC1 and PKC in RAW264.7 cells. But in P388D1 cells, although PKC, PKC and PKC were down-regulated, the expression of PKC1 and PKC2 could not be regulated. Comparing with LPS-induced IL-1, TNF- and NO production by the two macrophage cell lines, P388D1 failed to produce NO. In RAW264.7 cells, LPS-induced NO production and antitumor activity was attenuated by the addition of L-NAME, an iNOS inhibitor. Conclusion: The results indicated a critical role of PKC in LPS-induced antitumor activity and this cytotoxicity is mainly due to PKC- mediated NO production by RAW264.7 cells, but not a direct cytotoxic activity.

Analysis of Gene Expression of Seven Isoforms of ADP-glucose Pyrophosphorylase in Rice Endosperm under Different Temperature Conditions

[Objective] This study aimed to analyze the effects of temperature on the expression of AGPase isoform genes in rice endosperm during milk stage. [Method] Different temperature treatments （33 and 25 ℃ of daily mean temperature for high and normal temperature treatments, respectively） and the real-time fluorescence quantitative PCR （ FQPCR） were used to analyze the expression patterns of seven isoforms （AGPS1, AGPS2a, AGPS2b, AGPL1, AGPL2, AGPL3 and AGPL4） of ADPglucose pyrophosphorylase （AGPase） which was the key enzyme in starch synthesis and metabolism in rice endosperm of two rice varieties Teqing and Thai Fragrant Rice. [Result] The AGPase isoforms AGPS2b, AGPL2 and AGPL3 had much higher expression than the other four isoforms, thus they were thought to be the main expression patterns of AGPase in rice endosperm. The relative expressions of AGPL2 was the highest among all the isoforms. The relative expressions of AGPS2b, AGPL2 and AGPL3 were higher in the normal temperature treatment than in the high temperature treatment in both rice varieties. The relative expression of the three enzyme genes in milk stages in Teqing was higher than those in Thai Fragrant Rice under different temperature treatments. [Conclusion] This study provides a theoretical basis for further use of molecular biology techniques to cultivate stable high-quality rice varieties.

怀玉山三叶青TOM2BisoformX1基因克隆和功能分析

为揭示怀玉山三叶青TOM2BisoformX1(tobamovirusmultiplicationprotein2BisoformX1)的生物学功能提供理论依据,本研究通过怀玉山三叶青试管苗转录组数据库筛选到怀玉山三叶青TOM2BisoformX1基因的核心片段,利用RT-PCR技术克隆了该基因,并采用生物信息学、转基因瞬时表达和实时定量PCR方法对其进行序列分析、亚细胞定位、组织表达分析和功能分析。结果表明,怀玉山三叶青TOM2BisoformX1基因cDNA总长度为432bp,G+C含量为50.46%;编码143个氨基酸,分子量15392.36Da,等电点7.87,为亲水性蛋白;二级结构由α-螺旋(50.35%)、β-片层(2.10%)、无规则卷曲(47.55%)构成;三级结构为单体;预测怀玉山三叶青TOM2BisoformX1主要存在于细胞核中;怀玉山三叶青TOM2BisoformX1与葡萄(Vitis vinifera)TOM2BisoformX1(GenBank:XP_010664025.1)的同源性最高,达到83.92%。通过烟草叶片亚细胞定位分析表明,TOM2BisoformX1定位于细胞质和细胞核中。实时定量PCR结果显示,TOM2BisoformX1基因在怀玉山三叶青两个栽培种中的表达存在器官特异性,‘怀玉2号’和‘怀玉1号’均在叶中表达量最高;TOM2BisoformX1转基因阳性烟草的三叶青花叶病毒表达量显著高于TOM2BisoformX1转基因阴性烟草;与转基因阴性烟草相比,转基因阳性烟草的净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)、最大光化学效率(Fv/Fm)、实际光化学量子效率(ΦPSⅡ)、光化学淬灭系数(qP)及电子传递效率(ETR)显著下降,而非光化学淬灭系数(NPQ)显著上升。怀玉山三叶青TOM2BisoformX1具有典型TOM2BisoformX1的结构特征,氨基酸序列及核酸序列与同源物种相似度高,进化上高度保守,且可促进三叶青烟草花叶病毒的增殖,降低植株的光合作用效率。

Androgen receptor isoforms in human and rat prostate

Aim: To investigate the androgen receptor (AR) isoforms and its variability of expression in human and rat prostatictissues. Methods: Human benign prostatic hyperplasia (BPH) and prostatic cancer tissues were obtained from pa-tients undergoing prostatectomy, and rat ventral prostate was incised 3 days after castration. Forty-one AR-positive BPHspecimens, 3 prostatic cancer specimens, and 6 rat prostates were used. After processing at 4℃, the tissues were ex-amined by means of high resolution isoelectric focusing (IEF) technique to determine their AR isoforms. Results:From the prostatic specimens, 3 types of AR isoforms were detected with pI values at 6.5, 6.0, and 5.3. In humanBPH tissues, 15/41 (36.6%) specimens showed all the three types of isoforms, while 19/41 (46.3%) showed 2 iso-fora at various combinations and 7/41 (17.1%), 1 isoform. For the 3 prostatic cancer specimens, one showed 3 iso-forms, one, 2 isoforms, and the other failed to show any isoform. All rat prostatic tissues showed 2 isoforms at differ-ent combinations. Binding of ~3H-dihydrotestosterone (DHT) to the isoforms was inhibited by the addition of 100-foldexcess of DHT or testosterone, but not progesterone, oestradiol or diethylstilboestrol. Conclusion: AR isoforms aredifferent in different patients. Although their genesis is not clear, the therapeutic implication of the present observationappears to be interesting, that may help clarifying the individual differences in the response to hormonal therapy.(Asian J Androl 2000 Dec; 2: 307-310)

Survivin isoforms and clinicopathological characteristics in colorectal adenocarcinomas using real-time qPCR

AIM:To investigate three isoforms of survivin in colorectal adenocarcinomas.METHODS:We used the LightCycler Technology(Roche),along with a common forward primer and reverse primers specific for the splice variants and two common hybridization probes labeled with fluorescein and LightCycler-Red fluorophore(LC-Red 640).Real time quantitative polymerase chain reaction(PCR) was performed on cDNAs from 52 tumor specimens from colorectal cancer patients and 10 unrelated normal colorectal tissues.In the patients group,carcinoembryonic antigen(CEA) and CA19-9 tumor markers were also measured immunochemically.RESULTS:Wild type survivin mRNA isoform was expressed in 48%of the 52 tumor samples,survivin-2b in 38%and survivin-ΔΕx3 in 29%,while no expression was found in normal tissues.The mRNA expression of wild type survivin presented a significant correlation with the expression of the ratio of survivin-2b,survivin-ΔΕx3,survivin-2b/wild type survivin and survivin-ΔΕx3/wild type survivin(P<0.001).The mRNA expression of wildsurvivin and survivin-ΔΕx3 was related with tumor size and invasion(P=0.006 and P<0.005,respectively).A significant difference was found between survivin-2b and morphologic cancer type.Also,the ratio of survivin-ΔEx3/ wild-survivin was significantly associated with prognosis.No association was observed between the three isoforms and grade,metastasis,Dukes stage and gender.The three isoforms were not correlated with CEA and CA19-9.CONCLUSION:Survivin isoforms may play a role in cell apoptosis and their quantification could provide information about clinical management of patients suffering from colorectal cancer.

Role of PRMTs in cancer: Could minor isoforms be leaving a mark?

Protein arginine methyltransferases(PRMTs) catalyze the methylation of a variety of protein substrates, many of which have been linked to the development, progression and aggressiveness of different types of cancer. Moreover, aberrant expression of PRMTs has been observed in several cancer types. While the link between PRMTs and cancer is a relatively new area of interest, the functional implications documented thus far warrant further investigations into its therapeutic potential. However, the expression of these enzymes and the regulation of their activity in cancer are still significantly understudied. Currently there are nine main members of the PRMT family. Further, the existence of alternatively spliced isoforms for several of these family members provides an additional layer of complexity. Specifically, PRMT1, PRMT2, CARM1 and PRMT7 have been shown to have alternative isoforms and others may be currently unrealized. Our knowledge with respect to the relative expression and the specific functions of these isoforms is largely lacking and needs attention. Here we present a review of the current knowledge of theknown alternative PRMT isoforms and provide a rationale for how they may impact on cancer and represent potentially useful targets for the development of novel therapeutic strategies.

Identification of the metabolite and cytochrome P450 isoforms involved in rat liver microsomal metabolism of TM208

To identify the metabolite and CYP450 isoforms involved in rat liver microsomal metabolism of TM208. The present study investigated the metabolism of TM208 and the effects of selective CYP450 inhibitors on the metabolism of TM208 in rat liver microsomes. Various specific inhibitors of CYP were used to identify the isoforms of CYP involved in the metabolism of TM208. The inhibitor of CYP2D and that of CYP2B had strong inhibitory effects on TM208 metabolism in a concentration-de- pendant manner, the inhibitor of CYP1A had a modest inhibitory effect, and the inhibitor of CYP3A seemed not to have an obvious inhibitory effect on TM208 metabolism. TM208 might mainly be metabolized by CYP2D and CYP2B in rat liver microsomes.

Characterization of four hemocyanin isoforms in Litopenaeus vannamei

In this study, the gene encoding hemocyanin subunit L, Lv Hc L, was cloned from Litopenaeus vannamei and the genomic organization was characterized. This gene was diverse with many SNPs and also had at least four isoforms, while one of them（Lv Hc L4） only had two exons and the exon2 was missed. Transcription analysis showed that these isoforms of Lv Hc L were up-regulated after WSSV challenge in WSSV-resistant shrimp, while the transcriptions were decreased constantly in WSSV-susceptible shrimp. It is suggested that the hemocyanin had rich polymorphism and was involved in the antiviral response. These results could extend our previous findings and provide insights into the immune feature of hemocyanin, which would be helpful for further studies aimed at antiviral mechanism in invertebrate.

Role of Δ133p53 isoform in NF-κB inhibitor PDTC-mediated growth inhibition of MKN45 gastric cancer cells

AIM To investigate the role of Δ133p53 isoform in nuclear factor-κB(NF-κB) inhibitor pyrrolidine dithiocarbamate(PDTC)-mediated growth inhibition of MKN45 gastric cancer cells.METHODS The growth rate of MKN45 cells after treatment with different concentrations of only PDTC or PTDC in combination with cisplatin was detected by the CCK-8 assay. m RNA expression levels of Δ133p53, p53β, and the NF-κB p65 subunit and p65 protein levels were detected by reverse transcription-polymerase chain reaction(RT-PCR) and immunofluorescence, respectively. Growth of MKN45 cells was significantly inhibited by PDTC alone in a dose-dependent manner(P < 0.01). Moreover, the inhibitory effect of cisplatin was remarkably enhanced in a dose-dependent manner by co-treatment with PDTC(P < 0.01).RESULTS RT-PCR analysis revealed that m RNA expression of p65 was curbed significantly in a dose-dependent manner by treatment with only PDTC(P < 0.01), and this suppressive effect was further enhanced when co-treated with cisplatin(P < 0.01). With respect to the other p53 isoforms, m RNA level of Δ133p53 was significantly reduced in a dose-dependent manner by treatment with only PDTC or PTDC in combination with cisplatin(P < 0.01), whereas p53β m RNA expression was not altered by PDTC treatment(P > 0.05). A similar tendency of change in p65 protein expression, as observed for the corresponding m RNA, was detected by immunofluorescence analysis(P < 0.01). Pearson correlation analysis demonstrated that Δ133p53 and p65 m RNA expression levels were positively related, while no significant relationship was observed between those of p65 and p53β(r = 0.076, P > 0.01).CONCLUSIONΔ133p53 isoform(not p53β) is required in PDTCinduced inhibition of MKN45 gastric cancer cells, indicating that disturbance in the cross-talk between p53 and NF-κB pathways is a promising target in pharmaceutical research for the development of treatment strategies for gastric cancer.

Changes of Levels of Glutamine Synthetase Isoforms in Roots and Leaves in Responseto Nitrogen Fertilizer Application at Different Growth Stages in Irrigated Rice

Nitrogen is a key element to control the growth and yield of crops. Fertilizer urea nitrogen (N) 60,45, and 30 kg/hm2 was applied at three different stages, midtillering, panicle initiation, and flowering, of the growth and development of rice plants, respectively. At both midtillering and panicle initiation, the total activity of glutamine synthetase (GS) in rice roots and leaves was incrased remarkably as a result of a large amount of ammonia absorbed by roots. Native-PAGE and activity staining showed that the increase of total activity in rice roots and leaves was due to the synthesis of GSrb in roots and GS2 in leaves and that the activity of GSra in roots and GS1 in leaves remained constant. The results showed that the assimilation of external nitrogen was carried out by GSrb but not GSra in rice roots and that the activitry of GS2 was induced also by the external nitrogen, and that GSrb played main role in meeting the needs of the rapid tillering for nitrogen. At flowering, the activity of GS in rice roots and leaves did not change almost after topdressing. These rssults suggest that the change of GS activity in rice roots may use as a measure of the utilization efficiency of the fertilizer.

ApoE isoforms,treatment of diabetes and the risk of coronary heart disease

AIM:To analyze the risk of coronary heart disease in patients with type 2 diabetes mellitus(T2DM)receiving standard medical treatment.METHODS:We performed a retrospective chart analysis of 269 middle-aged patients(age 45-64 years,mean age,53.9±5.5 years)with T2DM and without atherosclerotic cardiovascular events who underwent typing to determine their apolipoprotein E(apoE)isoforms.The apoE isoforms were determined using isoelectric focusing,followed by immunoblotting.We retrospectively evaluated the charts of the 269 patients,recorded between their first visit to the hospital(the study's start point,between 1987 and 1992)and the occurrence of an atherosclerotic cardiovascular event(the study's endpoint)or January 2004,whichever came first.The age-adjusted mean values and the prevalences of covariates were calculated to compare the laboratory data among the apoE phenotypes.To investigate the association of risk factors with the incidence of coronary heart disease during the follow-up period,monovariate and multivariate Cox regression models were used.RESULTS:At enrollment,the mean serum low density lipoprotein(LDL)cholesterol levels were lowest(2.92± 0.89 mmol/L)among the subjects with apoE2(apoE2/2 or apoE2/3)and highest(3.52±0.77 mmol/L)among the subjects with apoE4(apoE3/4 or apoE4/4).No significant differences in mean age or the percentage of smokers were observed among the three groups.Furthermore,no significant differences were observed in the systolic and diastolic blood pressures,body mass index,HbA1c level or serum triglyceride levels among the three groups.There were 47 cases of coronary heart disease over 3285 person-years of follow-up.An age-adjusted multivariate Cox proportional model identified diabetic retinopathy(hazard ratio,2.38,95% CI:1.28-4.43,P=0.006),a high systolic blood pressure(hazard ratio,1.04,95%CI:1.02-1.06,P<0.001) and high HbA1c values(hazard ratio,1.19,95%CI:1.02-1.38,P=0.0029),but not the LDL cholesterol value at enrollment(hazard ratio,1.01,95%CI:0.97-1.05,P=0.77)nor the specific apoE isoform,as significant predictors of coronary heart disease.CONCLUSION:Under standard medical treatment of diabetes,including the control of LDL cholesterol levels,the apoE4 isoform was not associated with coronary heart disease among T2DM patients.

Aberrant expression of alternative isoforms of transcription factors in hepatocellular carcinoma

Hepatocellular carcinoma(HCC) is one of the most prevalent malignancies worldwide and the second leading cause of death among all cancer types. Deregulation of the networks of tissue-specific transcription factors(TFs) observed in HCC leads to profound changes in the hepatic transcriptional program that facilitates tumor progression. In addition, recent reports suggest that substantial aberrations in the production of TF isoforms occur in HCC. In vitro experiments have identified distinct isoform-specific regulatory functions and related biological effects of liver-specific TFs that are implicated in carcinogenesis, which may be relevant for tumor progression and clinical outcome. This study reviews available data on the expression of isoforms of liver-specific and ubiquitous TFs in the liver and HCC and their effects, including HNF4α, C/EBPs, p73 and TCF7 L2, and indicates that assessment of the ratio of isoforms and targeting specific TF variants may be beneficial for the prognosis and treatment of HCC.

Temperature Stress at Grain Filling Stage Mediates Expression of Three Isoform Genes Encoding Starch Branching Enzymes in Rice Endosperm

An early-maturity indica rice variety Zhefu 49, whose grain quality and starch structure are sensitive to environmental temperature, was subjected to different temperatures （32℃ for high temperature and 22℃ for optimum temperature） at the grain filling stage in plant growth chambers, and the different expressions of three isoform genes （SBEI, SBEIII and SBE/V） encoding starch branching enzyme （SBE） in the endosperms were studied by the real-time fluorescence quantitative PCR （FQ-PCR） method. Effects of high temperature on the SBE expression in developing rice endosperrns were isoform-dependent. High temperature significantly down-regulated the expressions of SBEI and SBEIII, while up-regulated the expression of SBEIV. Compared with SBEIV and SBEIII, the expression of SBEI gene in Zhefu 49 rice endosperms was more sensitive to temperature variation at the grain filling stage. This study indicates that changes in weather/climate conditions especially temperature stress influence rice grain formation and its quality as evidenced by isoform expression.

RNA secondary structures located in the interchromosomal region of human ACAT1 chimeric mRNA are required to produce the 56-kDa isoform

We have previously reported that the human ACAT1 gene produces a chimeric mRNA through the interchromosomal processing of two discontinuous RNAs transcribed from chromosomes 1 and 7. The chimeric mRNA uses AUG1397-1399 and GGC1274-1276 as translation initiation codons to produce normal 50-kDa ACAT1 and a novel enzymatically active 56-kDa isoform, respectively, with the latter being authentically present in human cells, including human monocyte- derived macrophages. In this work, we report that RNA secondary structures located in the vicinity of the GGC1274-1276 codon are required for production of the 56-kDa isoform. The effects of the three predicted stem-loops （nt 1255-1268, 1286-1342 and 1355-1384） were tested individually by transfecting expression plasmids into cells that contained the wild-type, deleted or mutant stem-loop sequences linked to a partial ACAT1 AUG open reading frame （ORF） or to the ORFs of other genes. The expression patterns were monitored by western blot analyses. We found that the upstream stem-loop1255-1268 from chromosome 7 and downstream stem-loop1286-1342 from chromosome 1 were needed for production of the 56-kDa isoform, whereas the last stem-loop135s-1384 from chromosome 1 was dispensable. The results of experi- ments using both monocistronic and bicistronic vectors with a stable hairpin showed that translation initiation from the GGC1274-1276 codon was mediated by an internal ribosome entry site （IRES）. Further experiments revealed that translation initiation from the GGC1274-1276 codon requires the upstream AU-constituted RNA secondary structure and the downstream GC-rich structure. This mechanistic work provides further support for the biological significance of the chimeric nature of the human ACAT1 transcript.

Identification and characterization of a novel isoform of hepatopoietin

AIM: To isolate a novel isoform of human HPO (HPO-205) from human fetal liver Marathon-ready cDNA and characterize its primary biological function. METHODS: 5'-RACE (rapid amplification of cDNA 5' ends) was used to isolate a novel isoform of hHPO in this paper. The constructed pcDNA(HPO-205), pcDNA(HPO) and pcDNA eukaryotic expression vectors were respectively transfected by lipofectamine method and the stimulation of DNA synthesis was observed by (3)H-TdR incorporation assay. Proteins extracted from different cells were analyzed by Western blot. RESULTS: A novel isoform of hHPO (HPO-205) encoding a 205 amino acid ORF corresponding to a translated production of 23 kDa was isolated and distinguished from the previous HPO that lacked the N-terminal 80 amino acids. The dose-dependent stimulation of DNA synthesis of HepG2 hepatoma cells by HPO-205 demonstrated its similar biological activity with HPO in vitro. The level of MAPK (Mitogen-activated protein kinase) phosphorylation by Western blot analysis revealed that HPO-205 might have the stronger activity of stimulating hepatic cell proliferation than that of HPO. CONCLUSION: A novel isoform of hHPO (HPO-205) was isolated from hepatic-derived cells. The comparison of HPO-205 and HPO will lead to a new insight into the structure and function of hHPO, and provide the new way of thinking to deeply elucidate the biological roles of HPO/ALR.

Soluble expression and characterization of a GFP-fused pea actin isoform (PEAc1)

A pea actin isoform PEAc1 with green fluorescent protein (GFP) fusion to its C-terminus and His-tag to its N- terminus, was expressed in prokaryotic cells in soluble form, and highly purified with Ni-Chelating SepharoseTM Fast Flow column. The purified fusion protein (PEAc1-GFP) efficiently inhibited DNase I activities before polymerization, and activated the myosin Mg-ATPase activities after polymerization. The PEAc1-GFP also polymerized into green fluorescent filamentous structures with a critical concentration of 0.75 μM. These filamentous structures were labeled by TRITC-phalloidin, a specific agent for staining actin microfilaments, and identified as having 9 nm diameters by negative staining. These results indicated that PEAc1 preserved the essential characteristics of actin even with His-tag and GFP fusion, suggesting a promising potential to use GFP fusion protein in obtainning soluble plant actin isoform to analyze its physical and biochemical properties in vitro. The PEAc1-GFP was also expressed in tobacco BY2 cells, which offers a new pathway for further studying its distribution and function in vivo.

Overexpression of the M2 isoform of pyruvate kinase is an adverse prognostic factor for signet ring cell gastric cancer

AIM:To investigate M2 isoform of pyruvate kinase(PKM2) expression in gastric cancers and evaluate its potential as a prognostic biomarker and an anticancer target.METHODS:All tissue samples were derived from gastric cancer patients underwent curative gastrectomy as a primary treatment.Clinical and pathological information were obtained from the medical records.Gene expression microarray data from 60 cancer and 19 noncancer gastric tissues were analyzed to evaluate the expression level of PKM2 mRNA.Tissue microarrays were constructed from 368 gastric cancer patients.Immunohistochemistry was used to measure PKM2 expression and PKM2 positivity of cancer was determined by proportion of PKM2-positive tumor cells and staining intensity.Association between PKM2 expression and the clinicopathological factors was evaluated and the correlation between PKM2 and cancer prognosis was evaluated.RESULTS:PKM2 mRNA levels were increased more than 2-fold in primary gastric cancers compared to adjacent normal tissues from the same patients(log transformed expression level:7.6 ± 0.65 vs 6.3 ± 0.51,P < 0.001).Moreover,differentiated type cancers had significantly higher PKM2 mRNA compared to undifferentiated type cancers(log transformed expression level:7.8 ± 0.70 vs 6.7 ± 0.71,P < 0.001).PKM2 protein was mainly localized in the cytoplasm of primary cancer cells and detected in 144 of 368(39.1%) human gastric cancer cases.PKM2 expression was not related with stage(P = 0.811),but strongly correlated with gastric cancer differentiation(P < 0.001).Differentiated type cancers expressed more PKM2 protein than did the undifferentiated ones.Well differentiated adenocarcinoma showed 63.6% PKM2-positive cells;in contrast,signet-ring cell cancers showed only 17.7% PKM2-positive cells.Importantly,PKM2 expression was correlated with shorter overall survival(P < 0.05) independent of stage only in signet-ring cell cancers.CONCLUSION:PKM2 expression might be an adverse prognostic factor for signet-ring cell carcinomas.Its function and potential as a prognostic marker should be further verified in gastric cancer.